STRUCTURE OF SODIUM DIAQUOBIS(BENZENE-1,2-DIOXYDIACETATO)LANTHANATE(III) TETRAHYDRATE

The crystal structure of sodium [diaquobis(benzene-1, 2-dioxydiacetato)lanthanate(III)] tetrahydrate, Na[La(H2-O)2(C10H8O6)2MH2O, is reported. Crystals obtained from aqueous solution are triclinic, space group PI, with [FORMULA OMMIETD] Standard heavy-atom methods were employed in the structural solution. Full-matrix, least-squares refinement of the nonhydrogen atom parameters, based on 4337 counter-collected Fo's, led to a final R value of 0.041 and a final weighted R value of 0.054. The lanthanum ion is decacoordinate, with a primary coordination sphere comprised of two tetradentate benzene-1, 2-dioxydiacetate ligands and two water molecules. The coordination polyhedron about the lanthanum ion approximates a s-bicapped square antiprism, with typical La-0 separations. Individual sodium ions are hexacoordinate, and inversion-related sodium coordination polyhedra together form a distorted, edge-shared bioctahedron. The novel aspect of the structure is the multiple bridging between the lanthanum and sodim ion coordination spheres, primarily through the benzene- 1, 2-dioxydiacetate ligands. The molecular conformation of the lanthanum complex observed in this structure does not duplicate that found in solution by NMR techniques. These conformational differences are attributable to interactions involving the coordinating sodium ion and other crystal packing forces not expected to be present in solution. © 1979, American Chemical Society. All rights reserved.